Nanoparticulate active agent compositions are described in U.S. Pat. No. 5,145,684 (“the '684 patent”) as particles comprising a poorly soluble therapeutic or diagnostic agent having adsorbed onto or associated with the surface thereof a non-crosslinked surface stabilizer.
Methods of making nanoparticulate active agent compositions are described in, for example, U.S. Pat. Nos. 5,518,187 and 5,862,999, both for “Method of Grinding Pharmaceutical Substances;” U.S. Pat. No. 5,718,388, for “Continuous Method of Grinding Pharmaceutical Substances;” and U.S. Pat. No. 5,510,118 for “Process of Preparing Therapeutic Compositions Containing Nanoparticles.”
Nanoparticulate active agent compositions are also described, for example, in U.S. Pat. No. 5,298,262 for “Use of Ionic Cloud Point Modifiers to Prevent Particle Aggregation During Sterilization;” 5,302,401 for “Method to Reduce Particle Size Growth During Lyophilization;” 5,318,767 for “X-Ray Contrast Compositions Useful in Medical Imaging;” 5,326,552 for “Novel Formulation For Nanoparticulate X-Ray Blood Pool Contrast Agents Using High Molecular Weight Non-ionic Surfactants;” 5,328,404 for “Method of X-Ray Imaging Using Iodinated Aromatic Propanedioates;” 5,336,507 for “Use of Charged Phospholipids to Reduce Nanoparticle Aggregation;” 5,340,564 for “Formulations Comprising Olin 10-G to Prevent Particle Aggregation and Increase Stability;” U.S. Pat. No. 5,346,702 for “Use of Non-Ionic Cloud Point Modifiers to Minimize Nanoparticulate Aggregation During Sterilization;” 5,349,957 for “Preparation and Magnetic Properties of Very Small Magnetic-Dextran Particles;” 5,352,459 for “Use of Purified Surface Modifiers to Prevent Particle Aggregation During Sterilization;” 5,399,363 and 5,494,683, both for “Surface Modified Anticancer Nanoparticles;” U.S. Pat. No. 5,401,492 for “Water Insoluble Non-Magnetic Manganese Particles as Magnetic Resonance Enhancement Agents;” 5,429,824 for “Use of Tyloxapol as a Nanoparticulate Stabilizer;” 5,447,710 for “Method for Making Nanoparticulate X-Ray Blood Pool Contrast Agents Using High Molecular Weight Non-ionic Surfactants;” 5,451,393 for “X-Ray Contrast Compositions Useful in Medical Imaging;” 5,466,440 for “Formulations of Oral Gastrointestinal Diagnostic X-Ray Contrast Agents in Combination with Pharmaceutically Acceptable Clays;” 5,470,583 for “Method of Preparing Nanoparticle Compositions Containing Charged Phospholipids to Reduce Aggregation;” 5,472,683 for “Nanoparticulate Diagnostic Mixed Carbamic Anhydrides as X-Ray Contrast Agents for Blood Pool and Lymphatic System Imaging;” 5,500,204 for “Nanoparticulate Diagnostic Dimers as X-Ray Contrast Agents for Blood Pool and Lymphatic System Imaging;” 5,518,738 for “Nanoparticulate NSAID Formulations;” 5,521,218 for “Nanoparticulate Iododipamide Derivatives for Use as X-Ray Contrast Agents;” 5,525,328 for “Nanoparticulate Diagnostic Diatrizoxy Ester X-Ray Contrast Agents for Blood Pool and Lymphatic System Imaging;” 5,543,133 for “Process of Preparing X-Ray Contrast Compositions Containing Nanoparticles;” 5,552,160 for “Surface Modified NSAID Nanoparticles;” 5,560,931 for “Formulations of Compounds as Nanoparticulate Dispersions in Digestible Oils or Fatty Acids;” 5,565,188 for “Polyalkylene Block Copolymers as Surface Modifiers for Nanoparticles;” 5,569,448 for “Sulfated Non-ionic Block Copolymer Surfactant as Stabilizer Coatings for Nanoparticle Compositions;” 5,571,536 for “Formulations of Compounds as Nanoparticulate Dispersions in Digestible Oils or Fatty Acids;” 5,573,749 for “Nanoparticulate Diagnostic Mixed Carboxylic Anhydrides as X-Ray Contrast Agents for Blood Pool and Lymphatic System Imaging;” 5,573,750 for “Diagnostic Imaging X-Ray Contrast Agents;” U.S. Pat. No. 5,573,783 for “Redispersible Nanoparticulate Film Matrices With Protective Overcoats;” 5,580,579 for “Site-specific Adhesion Within the GI Tract Using Nanoparticles Stabilized by High Molecular Weight, Linear Poly(ethylene Oxide) Polymers;” 5,585,108 for “Formulations of Oral Gastrointestinal Therapeutic Agents in Combination with Pharmaceutically Acceptable Clays;” 5,587,143 for “Butylene Oxide-Ethylene Oxide Block Copolymers Surfactants as Stabilizer Coatings for Nanoparticulate Compositions;” 5,591,456 for “Milled Naproxen with Hydroxypropyl Cellulose as Dispersion Stabilizer;” 5,593,657 for “Novel Barium Salt Formulations Stabilized by Non-ionic and Anionic Stabilizers;” U.S. Pat. No. 5,622,938 for “Sugar Based Surfactant for Nanocrystals;” 5,628,981 for “Improved Formulations of Oral Gastrointestinal Diagnostic X-Ray Contrast Agents and Oral Gastrointestinal Therapeutic Agents;” 5,643,552 for “Nanoparticulate Diagnostic Mixed Carbonic Anhydrides as X-Ray Contrast Agents for Blood Pool and Lymphatic System Imaging;” 5,718,388 for “Continuous Method of Grinding Pharmaceutical Substances;” 5,718,919 for “Nanoparticles Containing the R(−) Enantiomer of Ibuprofen;” 5,747,001 for “Aerosols Containing Beelomethasone Nanoparticle Dispersions;” 5,834,025 for “Reduction of Intravenously Administered Nanoparticulate Formulation Induced Adverse Physiological Reactions;” 6,045,829 “Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors Using Cellulosic Surface Stabilizers;” 6,068,858 for “Methods of Making Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors Using Cellulosic Surface Stabilizers;” 6,153,225 for “Injectable Formulations of Nanoparticulate Naproxen;” 6,165,506 for “New Solid Dose Form of Nanoparticulate Naproxen;” 6,221,400 for “Methods of Treating Mammals Using Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors;” 6,264,922 for “Nebulized Aerosols Containing Nanoparticle Dispersions;” 6,267,989 for “Methods for Preventing Crystal Growth and Particle Aggregation in Nanoparticle Compositions;” 6,270,806 for “Use of PEG-Derivatized Lipids as Surface Stabilizers for Nanoparticulate Compositions;” 6,316,029 for “Rapidly Disintegrating Solid Oral Dosage Form,” 6,375,986 for “Solid Dose Nanoparticulate Compositions Comprising a Synergistic Combination of a Polymeric Surface Stabilizer and Dioctyl Sodium Sulfosuccinate;” 6,428,814 for “Bioadhesive Nanoparticulate Compositions Having Cationic Surface Stabilizers;” 6,431,478 for “Small Scale Mill;” 6,432,381 for “Methods for Targeting Drug Delivery to the Upper and/or Lower Gastrointestinal Tract,” U.S. Pat. No. 6,592,903 for “Nanoparticulate Dispersions Comprising a Synergistic Combination of a Polymeric Surface Stabilizer and Dioctyl Sodium Sulfosuccinate,” 6,582,285 for “Apparatus for sanitary wet milling;” 6,656,504 for “Nanoparticulate Compositions Comprising Amorphous Cyclosporine;” 6,742,734 for “System and Method for Milling Materials;” 6,745,962 for “Small Scale Mill and Method Thereof;” 6,811,767 for “Liquid droplet aerosols of nanoparticulate drugs;” 6,908,626 for “Compositions having a combination of immediate release and controlled release characteristics;” 6,969,529 for “Nanoparticulate compositions comprising copolymers of vinyl pyrrolidone and vinyl acetate as surface stabilizers;” and 6,976,647 for “System and Method for Milling Materials,” 6,991,191 for “Method of Using a Small Scale Mill;” 7,101,576 for “Nanoparticulate Megestrol Formulation,” U.S. Pat. No. 7,198,795 for “In vitro methods for evaluating the in vivo effectiveness of dosage forms of microparticulate of nanoparticulate active agent compositions;” 7,244,451 for “Methods of making nanoparticulate drug compositions comprising copolymers of vinyl pyrrolidone and vinyl acetate as surface stabilizers”; U.S. Pat. No. 7,276,249 for “Nanoparticulate Fibrate Formulations”; 7,288,267 for “Bioadhesive nanoparticulate compositions having cationic surface stabilizers”; 7,320,802 for “Methods of treatment using nanoparticulate fenofibrate compositions”; and 7,390,505 for “Nanoparticulate topiramate formulations”, all of which are specifically incorporated by reference.
Meloxicam, also known as 4-hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2-H-1,2-benzothiazine-3-carboxamide 1,1-dioxide, is a member of the enolic acid group of nonsteroidal anti-inflammatory drugs (NSAIDs). Meloxicam is an oxicam derivative with the following chemical structure:

Meloxicam has an empirical formula of C14H13N3O4S2 and a molecular weight of 351.41. See The Physicians' Desk Reference, 56th Ed., pp. 1054 (2002); and The Merck Index, 13th Ed., pp. 1040-1041 (Merck & Co. 2001). Meloxicam is practically insoluble in water with higher solubility observed in strong acids and bases. It is very slightly soluble in methanol. The Physicians' Desk Reference, 56th Ed., pp. 1054.
4-hydroxy-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxides and salts thereof, as well as methods of preparing these compounds, pharmaceutical compositions containing them as active ingredients, and methods of using them as antiphlogistics, are discussed in U.S. Pat. No. 4,233,299, herein incorporated by reference. The pharmacology of meloxicam in horses is discussed in Lees et al., Brit. Vet. J., 147: 97 (1991); veterinary trials in dogs are discussed in Henderson et al., Prakt. Tierarzt., 75:179 (1994); the physiochemical properties of meloxicam are discussed in Tsai et al., Helv. Chim. Acta, 76:842 (1993); the pharmacology, mechanism of action, and clinical efficacy are discussed in Brit. J. Rheumatol., 35(Suppl. 1): 1-77 (1996); and clinical trials of gastrointestinal tolerability in arthritis is discussed in Hawkey et al., Brit. J. Rheumatol., 37:937 (1998), and Dequeker et al., Brit. J. Rheumatol., 37:946 (1998).
Meloxicam exhibits anti-inflammatory, analgesic, and antifebrile activities. Like other NSAIDs, the primary mechanism of action of meloxicam is via inhibition of the cyclooxygenase (COX-2) enzyme system resulting in decreased prostaglandin synthesis. See The Physicians' Desk Reference, 56th Ed., pp. 1054 (2002). In contrast, COX-2 is not present in healthy tissue and its expression is induced in certain inflammatory states. See Vane et al., Proc. Natl. Acad. Sci. USA, 91:2046-2050 (1994); Oulette et al., Proc. Natl. Acad. Sci., 98:14583-14588 (2001); and Seibert et al., Proc. Natl. Acad. Sci., 91:12013-12017 (1994).
The pathological production of prostaglandins by COX-2 is implicated in a number of human disease states, including rheumatoid arthritis, osteoarthritis, pyrexia, asthma, bone resorption, cardiovascular diseases, nephrotoxicity, atherosclerosis, and hypotension. Id. Elevated levels of prostaglandins enhance or prolong pro-inflammatory signals which cause the pain, stiffness, and inflammation associated with these conditions. See Smith et al., Proc. Natl. Acad. Sci., 95:13313-13318 (1998).
Meloxicam is superior to traditional non-selective NSAIDs because it selectively inhibits COX-2, thus causing fewer gastrointestinal problems such as bleeding, heartburn, reflux, diarrhea, nausea, and abdominal pain. Meloxicam preferentially inhibits COX-2 with a COX-2/COX-1 inhibition ratio of 0.09. It is desirable to selectively inhibit COX-2 and the pathological production of prostaglandins for which that enzyme is responsible because the therapeutic analgesic/anti-inflammatory properties of NSAIDs occur by inhibition of inducible COX-2 at the site of inflammation. Conversely, the majority of adverse drug reactions to NSAIDs, including gastrointestinal ulcers and renal failure, result from inhibition of the constitutive COX-1 enzymes. This is because as a result of such COX-1 inhibition, prostaglandins necessary for gastric mucosal production and renal blood circulation are not produced. See Vane et al., Proc. Natl. Acad. Sci. USA, 91:2046 (1994); Oulette et al., Proc. Natl. Acad. Sci., 98:14583 (2001); and Seibert et al., Proc. Natl. Acad. Sci., 91:12013 (1994). Compounds that selectively inhibit the biosynthesis of prostaglandins by inhibiting the activity of the inducible enzyme, COX-2, exert anti-inflammatory effects without the adverse side effects associated with COX-1 inhibition.
Some of the trade names under which a commercially available meloxicam product has been or is marketed include MOBIC®, MOBEC®, MOBICOX®, MOVALIS®, and MOVATEC®. Meloxicam has been shown to be useful in the symptomatic treatment of painful osteoarthritis (arthrosis, degenerative joint disease), symptomatic treatment of rheumatoid arthritis, symptomatic treatment of ankylosing spondylitis, and symptomatic treatment of the signs and symptoms of osteoarthritis, including pain, stiffness, and inflammation.
The form of meloxicam currently marketed in the United States is MOBIC® (Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Conn.), provided in 7.5 and 15 mg tablets. The bioavailability of a single 30 mg oral dose is 89% as compared to a 30 mg intravenous bolus injection. The pharmacokinetics of a single intravenous dose of meloxicam is dose-proportional in the range of 5 to 60 mg. See The Physicians' Desk Reference, 56th Ed., pp. 1054 (2002). After administration of multiple oral doses of meloxicam, the pharmacokinetics is dose-proportional in the range of 7.5 to 15 mg. The rate or extent of absorption is not affected by multiple dose administration. Under fasted steady state conditions, the mean Cmax is achieved within four to five hours, with a second meloxicam concentration peak occurring at approximately twelve to fourteen hours post-dose, which suggests gastrointestinal recirculation. Under steady state fed conditions in healthy adult males, the 7.5 mg tablets have a mean Cmax of 1.05 μg/mL, a Tmax of 4.9 hrs, and a t½ of 20.1 hours. Under steady state fed conditions in elderly males and females, the 15 mg tablets have a Cmax of 2.3 and 3.2 μg/mL, respectively, a Tmax of 5 and 6 hrs, respectively, and a t½ of 21 and 24 hrs, respectively. See The Physicians' Desk Reference, 56th Ed., pp. 1054 (2002).
Meloxicam is useful in relieving the signs and symptoms of rheumatoid arthritis, lower back pain, and acute pain, e.g. treatment of post surgical pain, treatment of pain resulting from battle field wounds, and migraine headaches. Meloxicam may be especially effective for treatment of all types of pain associated with inflammation. In general meloxicam is effective for treatment of moderate to moderately severe acute pain as would be understood by a skilled practitioner.
NSAIDs, like meloxicam, are useful in pain management because NSAIDs provide an analgesic effect without the sedation and addictive properties of narcotic analgesics. Furthermore, the long t1/2 of meloxicam makes it useful for long-lasting relief which is not provided by narcotic analgesics. However, due to their typically long onset of action, conventional NSAIDs, including conventional meloxicam, are frequently inappropriate for management of acute pain.
Because meloxicam is practically insoluble in water, attaining sufficient bioavailability of this drug is problematic. Prior art methods of increasing the bioavailability of meloxicam include increasing its solubility by forming a cyclodextrin complex of the drug (see U.S. Pat. No. 6,284,269) or by forming a salt of meloxicam with an inorganic or organic base (U.S. Pat. Appln. Pub. No. US 2002/0035107 A1).
The skilled person knows that for any particulate composition to be approved by the FDA for intravenous (I.V.) or intramuscular (I.M.) administration, the composition must meet the standards set forth in General Chapter 788 of the United States Pharmacopoeia (“USP<788>”). Specifically, in the United States, any particulate matter injectable solution must comply with the particle size and number requirements of USP<788>. That is, under the approved “Light Obscuration” test set forth in USP<788>, known as “Method 1,” there must be: (i) no more than 6,000 particles in a particulate composition that are greater than 10 μm in size and (ii) no more than 600 particles that are greater than 25 μm in size. Under “Method 2,” the Microscopy test, a particulate composition must contain (i) no more than 3,000 particles in a particulate composition that are greater than 10 μm in size and (ii) no more than 300 particles that are greater than 25 μm in size. The theorized large particles represent the presence of aggregates of individual particles which clump together.
Because poorly water soluble active agents are difficult to solubilize in an aqueous based mammal environment, it can be difficult to formulate many poorly water soluble drugs for injectable formulations as conventional poorly water soluble drug formulations can contain particles of drug which do not meet the standards set forth in USP<788>. This is problematic, as an injectable formulation may be highly desirable over an alternative dosage form. For example, drugs taken orally may cause significant first pass liver damage, which can be avoided or minimized using an injectable dosage form. Particularly for pain medication, injectable dosage forms may be highly desirable due to the fast onset of activity.